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The correct answer is

(i) (a)

The most easly hydrolysed molecule under S_N2 reaction is Ten. butyl chloride.

(ii) b, c carbon atoms

If all the four atom or group of atoms attach to a carbon are different then carbon is called asymmetric carbon. e.g. CH₃CHBrCl. 

Correct answer is (b) 8

(b) Conc.HCl + Anhydrous ZnCl₂

Because HI produced get oxidize to Iodine in presence of Sulphuric acid.

Unable to form Hydrogen bond with water.

Haloalkanes aren't very soluble in water because they can't form hydrogen bonds, and the energy required to break hydrogen bonds in water etc is higher than the energy released when new bonds between the haloalkane and water are formed.

The decreasing order of boiling point of haloalkanes is CH₃I > CH₃Br > CH₃CI > CH₃F.

CH₃CH₂I (Iodoethane)+ HI _{\(\overset {Red \,P}{\overset{\longrightarrow}{Δ }}\)} CH₃ - CH₃(Ethane) + I₂

In Swarts reaction, chioroalkane is converted to Fluoroalkane.

(b) Swarts reaction

The catalyst used in the preparation of CC₂F₂ form CCl₄ and HF is SbCl₅ .

The formula of Freon - 12 is  CF₂Cl₂.

The formula fo Freon - 11 is CFCl₃.

(b) Freon : Propellant

(c) CH₃Br – aqueous KOH : E₂ reaction 

Reactions are given as

(i) CH₃ - CH₂Br (Bromo ethane) + KOH (aqueous) \(\overset{Boil}{\longrightarrow}\) CH₃ - CH₂OH (Ethanol) + KBr

(ii) CH₃- CH₂Br (Bromo ethane) + NH₃ \(\longrightarrow\)CH₃ - CH₂NH₂(Ethyl amine) + HBr

The correct order of boiling point of haloalkanes is:

CH₃CH₂CH₂Cl > CH₃CH₂Cl > CH₃Cl. 

The boiling point of monoalkanes increase with the increase in the number of carbon atoms.

The IUPAC name of DDT is 2,2-bis (4-chloropheny)-1,1.1-trichloroethane and tha of benzene hexachloride is 1,2,3,4,5,6-hexachlorocyclohexane.
They are banned in india because they are non-biodegradable. Instead, they get deposited and stored in fatty tissues. If this ingestion continues at a steady rate, DDT builds up within the animal over time. This will affects the reproductive system of animals.
If animals including humans are exposed to high levels of benzene hexachloride then it may cause acute poisoning. Apart from that this BHC may affect liver functioning in humans.

(b) Vinyl chloride

(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

a) iii) CH₃ – CH₂ = CH₂

b) Chloroform is slowly oxidised by air in the presence of light to an extremely poisonous gas, carbonyl chloride, also known as phosgene. It is therefore stored in closed dark coloured bottles completely filled so that air is kept out.

2CHCl₃+O₂ \(\overset{light}{\longrightarrow}\) 2COCl₂+2HCl

Methyl magnesium chloride (CH₃MgCI) – Grignard reagent

When ethyl alcohol is heated with thionyl chloride, chloro ethane is obtained. Here the byproducts are in gaseous state and hence this method is used for the preparation of extra pure alkyl halide.

CH₃-CH₂-OH + SOCI₂ → CH₃CH₂CI + HCI + SO₂

DDT prepared from chloral and chloro benzene.

(a) retension

The organic compound used as feed stock in the synthesise of chloro fluorocarbon is CCI₄

(i) Cl₂/UV light

(i) RX + NaI → RI + NaX

(ii) Electrophilic substitution reaction

The two reasons are as follows:

(i) Resonance effect : The electron pair of chlorine atom is involved in conjugation with the π-electrons of the benzene ring. As a result, electrons of C-Cl bond get delocalized and a partial double bond character develops in the bond and hence, it becomes difficult for the nucleophiie to cleave the C-Cl bond.

(ii) Increased electron density : A repulsion is suffered by the nucleophile due to increased electron density on the benzene ring which prohibits the nucleophile to make a close access for the attack on the molecule.

Chiorobenzene is reduced with Ni-Al Alloy in the presence of NaOH to give benzene.

C₆H₅Cl(Chlorobenzene) + 2(H) \(\underset{NaOH}{\stackrel{Ni-Al}{\longrightarrow}}\) C₆H₆ (Benzene) + HCl

The melting point of p-dichloro benzene is higher than the melting point of the corresponding ortho and mcta isomers. The higher melting which leads to more close packing of its molcules in the crystal lattice and consequently strong intermolecular attractive forces which requires more energy for melting. 

p-dichlorobenzene > o-dichlorobenzene > mdichlorobenzene

p- dichlorobenzene is symmetrical, fits into crystal lattice more readily and has higher melting point. 

(iii) Methanamine (CH₃NH₂)

1. Chlorobenzene is stabilised by resonance and there is negative charge on ‘Cl’ in 3 out of 5 resonating structures, therefore it has a lower dipole moment than cyclohexyl chloride in which there is no such negative charge. 

2. Alkyl halides cannot form H-bond with water and cannot break H-bonds between water molecules, therefore they are insoluble in water. 

3. Grignard reagents react with H₂O to form alkanes, therefore they are prepared under anhydrous conditions.

(a) chloromethane < Bromobenzene < Dibromo-methane < , Bromoform 

(b) Isopropyle chloride <1-chloropropane <1-Chlorobutane (As Branching increases , boiling point decreases)  

(iv) 1-Bromoethane < 1-Bromopropane < 1-Bromobutane < Bromobenzene

(i) Butane < 1-Chlorobutane < 1-Bromobutane < 1-Iodobutane

CH₂Cl₂ has the highest dipole moment since both the Cl- atoms are present on one side (on the head) of c – atom and therefore cause a maximum dipole moment.

In CHCl₃ and CCl₄, two Cl – atoms and four Cl – atoms cancel out their dipole moments.

1-Bromoethane < 1-Bromopropane < 1-Bromobutane < Bromobenzene Boiling point increases with increase in molecular mass of the alkyl halide.

(iii) Assertion is correct but reason is wrong statement.